1403545 - 10.29 - 163.58% Strings PerfIsASCIIHundred / Stylo Servo_DeclarationBlock_GetPropertyById_Bench (linux32, osx-10-10, windows10-64, windows7-32) regression on push ac60233276ed (Tue Sep 26 2017)

Status: VERIFIED FIXED

(Core :: CSS Parsing and Computation, defect)

Description

[Ionuț Goldan [:igoldan]]

We have detected a platform microbenchmarks regression from push:

https://hg.mozilla.org/integration/autoland/pushloghtml?fromchange=611582e42451dd26fcaa38f251e2203a6e8b0bf9&tochange=ac60233276ed2798c2f2f42772362f729dec3468

As author of one of the patches included in that push, we need your help to address this regression.

Regressions:

164%  Stylo Servo_DeclarationBlock_GetPropertyById_Bench linux32 opt      243,843.29 -> 642,725.30
161%  Stylo Servo_DeclarationBlock_GetPropertyById_Bench windows7-32 opt  224,732.54 -> 586,337.10
144%  Stylo Servo_DeclarationBlock_GetPropertyById_Bench windows10-64 opt 184,395.42 -> 449,097.60
130%  Stylo Servo_DeclarationBlock_GetPropertyById_Bench osx-10-10 opt    199,551.58 -> 457,979.75


You can find links to graphs and comparison views for each of the above tests at: https://treeherder.mozilla.org/perf.html#/alerts?id=9669

On the page above you can see an alert for each affected platform as well as a link to a graph showing the history of scores for this test. There is also a link to a treeherder page showing the jobs in a pushlog format.

To learn more about the regressing test(s), please see: https://developer.mozilla.org/en-US/docs/Mozilla/Performance/Automated_Performance_Testing_and_Sheriffing/Platform_Microbenchmarks

Comment 1

[Ionuț Goldan [:igoldan]]

Michael, I see you are the owner of the servo merge from https://github.com/servo/servo/pull/18642
Can we resolve these regressions? Or should we accept/backout them?

Comment 2

[Nika Layzell [:nika] (ni? for response)]

Attachment: Stop allocating in fmt::Write for nsA[C]String

I missed converting these locations when I made the previous patch, which caused an extra allocation to occur whenever using fmt::Write.

This should fix that issue.

MozReview-Commit-ID: 38WZKDU1cLg

Comment 3

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/1e3c2c6f12d1
Stop allocating in fmt::Write for nsA[C]String, r=froydnj

Comment 4

[Phil Ringnalda (:philor)]

https://hg.mozilla.org/mozilla-central/rev/1e3c2c6f12d1

Comment 5

[Ionuț Goldan [:igoldan]]

I confirm the fix resolved the regressions:

== Change summary for alert #9704 (as of September 27 2017 19:19 UTC) ==

Improvements:

 66%  Stylo Servo_DeclarationBlock_GetPropertyById_Bench linux32 opt      647,356.50 -> 219,750.67
 62%  Stylo Servo_DeclarationBlock_GetPropertyById_Bench windows7-32 opt  585,077.29 -> 225,259.44
 60%  Stylo Servo_DeclarationBlock_GetPropertyById_Bench linux64 opt      470,252.83 -> 188,702.18
 59%  Stylo Servo_DeclarationBlock_GetPropertyById_Bench windows10-64 opt 445,805.33 -> 184,229.44
 55%  Stylo Servo_DeclarationBlock_GetPropertyById_Bench osx-10-10 opt    456,356.33 -> 203,380.33

For up to date results, see: https://treeherder.mozilla.org/perf.html#/alerts?id=9704